The present invention relates to automotive bumper systems having beams and energy absorbers located on faces of the beams.
Many vehicle designs use energy absorbers positioned on a face or front surface of a steel bumper beam to improve energy absorption of a bumper system. The energy absorbers provide an initial level of energy absorption for low impact, including reducing damage during low impact, and also provide a supplemental level of energy absorption during high impact (i.e. before and at the time that the beam and vehicle begin to absorb substantial amounts of energy). Usually, the energy absorbers are fastened to the bumper beam with fasteners that assure accurate positioning of the energy absorber on the beam. The reasoning includes accurately positioning the energy absorber on the bumper beam to assure consistent performance, as well as to assure accurate positioning for aesthetics and assembly (e.g. to assure a good fit of the front-end fascia over the energy absorber and beam during assembly).
However, improvements are desired in terms of temporary and permanent attachment, and for improved and more reliable energy absorption. Typically, attachment of the energy absorber to bumper beams requires a plurality of mechanical fasteners. This is disadvantageous since mechanical fasteners require manual labor to install, which can add undesirably to cost. Also, the mechanical fasteners can result in localized and non-uniform stress distribution during impact, resulting in inconsistent collapse of the bumper system and poor energy absorption on impact. Further, fixing the energy absorber to the beams results in an inability of the energy absorber to shift and adjust to non-perpendicular and uneven loads transmitted from the impacting bodies. At the same time, depending on the bumper system, sometimes shifting of an energy absorber is not good since it can result in unpredictable, premature and non-uniform collapse, resulting in poor or inconsistent energy absorption by the bumper system.
Improvement is also desired for corner impact structure on bumper systems. Many existing bumper systems require that a front surface of an end of a bumper beam be shaped at an increased angle relative to the front of rest of the bumper beam to match an aerodynamic curvature of the vehicle at its front fender. One way to achieve this is by miter cutting an end of the bumper beam at an angle, and thereafter welding a plate onto the angled end to form a compound-angled flat front surface for supporting an energy absorber such as a foam cushion. Another way is to deform or crush an end of the bumper beam to form an angled front surface. Yet another way is to weld a bracket onto an end of the bumper beam, with the bracket extending longitudinally beyond the bumper beam to form the desired shape. However, all of these alternatives have drawbacks. For example, they each require a secondary operation, result in increased dimensional variation, and require significant investment in capital equipment. Further, they can lead to increased scrap, a substantial increase in manpower and manufacturing time, and substantial increase in inventories and work in process.
For all of the above reasons, there is a desire for bumper systems that yield a better, more consistent, more reliable, and greater impact energy absorption, both for low and high impact events, and also for square and skewed impact directions. Also, there is a desire for improvements facilitating assembly of an energy absorber to a beam, with lower cost and fewer parts, and with less labor. Still further, there is a desire for energy absorber designs that allows adjustment and tuning for optimal front end and corner impact strengths, even late in the bumper development program, and yet that do not require expensive or complex molding techniques or assembly techniques nor secondary miter cutting or crush forming bumper end sections. Still further, there is a desire for energy absorber designs that are adaptable for use with many different bumper beam cross-sectional shapes and sizes. Also, energy absorber designs are desired that are flexible and usable on non-linear bumper beams having different curvatures and longitudinal sweeps, and having different cross sections.
In one aspect of the present invention, a bumper system for vehicles includes a bumper beam and an energy absorber. The bumper beam has a continuous tubular cross section with top and bottom front walls defining a front surface that extends vertically when the bumper beam is in a car-mounted position and with top and bottom mid-walls defining a longitudinally-extending channel in the front surface between the top and bottom front walls. The energy absorber includes box-shaped sections that abut the front surface of the bumper beam and further includes rearwardly-extending nose sections that extend into the channel. In one form, the nose sections include collapse-controlling kick walls that lie along and abut the top and bottom mid-walls and that are connected to the box-shaped sections so that, upon impact by an object against the bumper system, the kick walls press into the top and bottom mid-walls with increasing force as the object strikes the box-shaped sections with increasing force. This structure results in a controlled flexure and collapse of the box-shaped sections of the polymeric energy absorber and of the top and bottom mid-walls of the bumper beam as a system.
In another aspect of the present invention, a bumper system for vehicles includes a bumper beam and an energy absorber. The bumper beam has a continuous tubular cross section with a front surface that extends vertically when the bumper beam is in a car-mounted position. The bumper beam has mid-walls extending to the front surface that form a longitudinally-extending channel across a middle area of the front surface. The energy absorber includes a rear surface abutting the front surface of the bumper beam. The energy absorber has first, second, third, and fourth parallel walls that extend horizontally, the first parallel wall being at a top location and the fourth parallel wall being at a bottom location. The energy absorber further includes top walls interconnecting the first and second parallel walls to form a top box section, and includes bottom walls interconnecting the third and fourth parallel walls to form a bottom box section. The energy absorber further has a nose section that extends rearwardly of the top and bottom walls into the bumper beam. The nose section includes kick walls that, upon impact against the bumper system, press laterally against the mid-walls of the bumper beam, causing the mid-walls and hence the bumper beam to collapse in a more controlled manner. By this arrangement, the collapse load of the beam is locally controlled for improved consistent collapse and energy absorption.
In another aspect of the present invention, a bumper system for vehicles includes a B-shaped bumper beam with a face and a longitudinally-extending channel in the face, and an energy absorber having energy-absorbing sections engaging the face. The energy absorber further includes at least one nose section connected to the energy-absorbing sections and that extends into the channel.
In still another aspect of the present invention, a bumper system for vehicles includes a bumper beam with a face and a channel in the face, and an energy absorber having first energy-absorbing sections engaging the face. The energy absorber further includes second energy-absorbing sections aligned with the channel, the second energy-absorbing sections being spaced from a bottom of the channel and being configured to move into contact with the bottom of the channel during an initial phase of an impact against the bumper system and further being configured to absorb energy during a later phase of the impact.
In yet another aspect of the present invention, a bumper system for vehicles includes a tubular bumper beam including a front face and open ends, and an energy absorber having a main section engaging the front face and end-covering corner sections connected to the main section that wrap around the open ends and cover the open ends. The corner sections each include walls defining a tubular section that extends in a direction generally perpendicular to a length of the tubular bumper beam, the walls being constructed to absorb energy upon corner impact against the bumper system.
In another aspect of the present invention, a bumper system for vehicles includes a bumper beam having a face, and an energy absorber engaging the face. The energy absorber has a plurality of spaced-apart box-shaped sections and a plurality of interconnecting sections connecting adjacent ones of the box-shaped sections. The box-shaped sections each have a top wall, a bottom wall, a right side wall, a left side wall, and a front wall that combine to form rearwardly-facing open boxes, and the interconnecting sections each have parallel walls extending in horizontal planes between adjacent ones of the right and left side walls and having a rear wall connecting the parallel walls to form a forwardly-open honeycomb structure. Selected ones of the side walls include crush-initiation apertures therein shaped to weaken the box-shaped sections to thus provide desired levels of energy absorption and force-versus-deflection characteristics along particular sections of the energy absorber during vehicle impacts and crashes.
In another aspect of the present invention, a bumper system for vehicles includes a bumper beam having a face defining a forward direction for a vehicle, and an energy absorber engaging the face. The energy absorber, when in a vehicle-mounted position, is symmetrically shaped about a transverse vertical central plane. The energy absorber includes a plurality of parallel walls that define horizontal planes and that extend longitudinally a complete length of the energy absorber except at the central plane, and the energy absorber further includes discontinuous front and rear walls that lie generally parallel the face and that interconnect the parallel walls to form open box-shaped sections to define an alternating arrangement of forward facing openings and rearward facing openings.
In another aspect of the present invention, a bumper system for vehicles includes a bumper beam having a face defining a forward direction for a vehicle and having open ends positioned close to and adapted to partially define front corners of a vehicle. An energy absorber engages the face. The energy absorber, when in a vehicle-mounted position, is symmetrically shaped about a transverse vertical central plane, and has a center section engaging the face and covering the face, and has corner sections covering the open ends of the bumper beam. The corner sections are formed in part by perpendicularly extending walls that form an open honeycomb shaped structure and being formed in part by a crescent shaped flange that extends outwardly from the perpendicularly extending walls.
In another aspect of the present invention, a bumper system for vehicles includes a bumper beam having a face defining a forward direction for a vehicle and having open ends. A pair of mounting brackets are attached to the bumper beam and are adapted to mount the bumper beam on a vehicle, with the mounting brackets each including a forwardly extending portion that extends at least partially over an associated one of the open ends. An energy absorber engages the face. The energy absorber, when in a vehicle-mounted position, is symmetrically shaped about a transverse vertical central plane. The energy absorber includes a pair of corner-forming end sections, each having a box-shaped section located in part between one of the open ends and the associated one of the forwardly extending portions of the mounting brackets.
In another aspect of the present invention, a bumper system for vehicles includes a bumper beam having a face defining a forward direction for a vehicle and having open ends. An energy absorber engages the face. The energy absorber, when in a vehicle-mounted position, is symmetrically shaped about a transverse vertical central plane. The energy absorber includes a center section and a pair of corner-forming sections attached to outer ends of the center section with a recessed area therebetween. A pair of mounting brackets are attached to the bumper beam and adapted to mount the bumper beam on a vehicle. The mounting brackets each include an outwardly extending portion that extends partially into the recessed area to support an associated one of the corner sections of the energy absorber during a corner impact.
In another aspect of the present invention, a method of developing a bumper system for vehicles, comprises steps of providing a bumper assembly including a bumper beam adapted for attachment to a vehicle and an energy absorber attached to the bumper beam, the energy absorber having a face defining a front-to-rear direction, and having a center section and corner-forming end sections, the center section and end sections having a plurality of box-shaped sections defined in part by planar wall sections that extend parallel the front-to-rear direction. The method further includes steps of impacting the bumper assembly with an object to simulate a vehicle crash and collecting impact data, analyzing the impact data and damage to the bumper assembly after the step of impacting, and adjusting impact strengths of individual ones of the box-shaped sections by forming holes and non-uniform apertures in the planar wall sections to reduce strengths of particular box-shaped sections.
In yet another aspect of the present invention, a bumper system for vehicles includes a bumper beam having a continuous tubular cross section with top, bottom, front and rear walls, with the front wall defining a front surface that extends generally vertically when the bumper beam is in a car-mounted position. The front wall includes apertures between the top and bottom front walls. An energy absorber is provided having a main body abutting the front surface and including box-shaped nose sections that extend through the apertures in the front surface of the bumper beam to locations proximate the rear wall. The box-shaped nose sections are configured to provide an initial amount of energy absorption during a vehicle impact and are configured to collapse with the bumper beam during later stages of the vehicle impact.
In yet another aspect of the present invention, a bumper system for vehicles includes a bumper beam having a continuous tubular cross section with top, bottom, front and rear walls, the front wall defining a front surface that extends generally vertically when the bumper beam is in a car-mounted position and the top and bottom walls extending generally horizontally. An energy absorber has a main body abutting the front surface and includes top and bottom flanges with friction pads engaging the top and bottom walls, respectively. The top and bottom flanges are relatively stiff but resilient and oriented to bias the friction pads with sufficient force to generate top and bottom opposing clamping forces on the bumper beam to temporarily retain the energy absorber on the bumper beam during assembly.
These and other aspects, objects, and features of the present invention will be understood and appreciated by those skilled in the art upon studying the following specification, claims, and appended drawings.